Magnetoresistance effect element having resistance adjusting layer and thin-film insertion layer

ABSTRACT

A magnetoresistance effect element includes a magnetoresistance effect film including a magnetically pinned layer having a magnetic material film whose direction of magnetization is pinned substantially in one direction, a magnetically free layer having a magnetic material film whose direction of magnetization changes in response to an external magnetic field, and a nonmagnetic metal intermediate layer located between said pinned layer and said free layer. The element also includes a pair of electrodes electrically connected to the magnetoresistance effect film to supply a sense current perpendicularly to a film plane of the magnetoresistance effect film. At least one of the pinned layer and the free layer may include a thin-film insertion layer. The nonmagnetic metal intermediate layer includes a resistance adjusting layer including at least one of oxides, nitrides and fluorides, and the thin-film insertion layer includes at least one element selected from the group consisting of iron (Fe), cobalt (Co) and nickel (Ni).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.11/283,873, filed Nov. 22, 2005, which is a divisional of U.S.application Ser. No. 10/887,080 filed Jul. 9, 2004, now U.S. Pat. No.7,072,522, which is a continuation of U.S. application Ser. No.10/217,410 filed Aug. 14, 2002, now U.S. Pat. No. 6,784,509, and isfurther based upon and claims the benefit of priority from the priorJapanese Patent Application No. 2001-246583, filed on Aug. 15, 2001. Theentire contents of each of the above applications are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

This invention relates to a magnetoresistance effect element, magnetichead and magnetic reproducing apparatus, and more particularly, to amagnetoresistance effect element structured to flow a sense currentperpendicularly of the film surface of a magnetoresistance effect film,as well as a magnetic head and a magnetic reproducing apparatus usingthe magnetoresistance effect element.

Read-out of information recorded in a magnetic recording mediumconventionally relied on a method of moving a reproducing magnetic headhaving a coil relative to the recording medium and detecting a currentinduced in the coil by electromagnetic induction then generated. Later,a magnetoresistance effect element was developed, and has been broughtinto practical use as a magnetic field sensor as well as a magnetic head(MR head) incorporated in a magnetic reproducing apparatus such as ahard disk drive.

For years, magnetic recording mediums have been progressively downsizedand enhanced in capacity, and the relative speed between the reproducingmagnetic head and the magnetic recording medium during informationread-out operation has been decreased accordingly. Under thecircumstances, there is the increasing expectation for MR heads capableof extracting large outputs even with small relative speeds.

As an answer to the expectation, it has been reported that multi-layeredfilms, so called an “artificial lattice films”, which are made byalternately depositing ferromagnetic metal films and nonmagnetic metalfilms, such as the combination of Fe layers and Cr layers or thecombination of Fe layers and Cu layers, under certain conditions, andbringing closely located ferromagnetic metal films intoantiferromagnetic coupling, exhibit giant magnetoresistance effects (seePhys. Rev. Lett. Vol. 61, p2474 (1988), Phys. Rev. Lett., Vol. 64, p2304(1990), for example). Artificial films, however, need a large magneticfield for magnetic saturation, and are not suitable as film materialsfor MR heads.

On the other hand, there are reports about realization of a largemagnetoresistance effect by using a multi-layered film of the sandwichstructure of a ferromagnetic layer on a nonmagnetic layer and aferromagnetic layer even when the ferromagnetic layer is not underferromagnetic coupling. According to this report, one of two layerssandwiching the nonmagnetic layer is fixed in magnetization beforehandby application of an exchanging bias magnetic field thereto, and theother ferromagnetic layer is magnetically reversed with an externalmagnetic field (signal magnetic field, for example). It results inchanging the relative angle between the magnetization directions ofthese two ferromagnetic layers on opposite surfaces of the nonmagneticlayer, and exerting a large magnetoresistance effect. The multi-layeredstructure of this kind is often called “spin valve” (see Phys. Rev. B,Vol. 45, p806 (1992), J. Appl. Phys., Vol. 69, p 4774 (1981) andothers).

Spin valves that can be magnetically saturated under a low magneticfield are suitable as MR heads and are already brought into practicaluse. However, their magnetoresistance ratios are only 20% maximum.Therefore, to cope with area recording densities not lower than 100Gbpsi (gigabits per square inch), there is the need of amagnetoresistance effect element having a higher magnetoresistanceratio.

Structures of magnetoresistance effect elements are classified into CIP(current-in-plane) type structures permitting a sense current to flow inparallel to the film plane of the element and CPP(current-perpendicular-to-plane) type structures permitting a sensecurrent to flow perpendicularly to the film plane of the element.Considering that CPP type magnetoresistance effect elements werereported to exhibit magnetoresistance ratios as large as approximatelyten times those of CIP type elements (J. Phys. Condens. Mater., Vol. 11,p. 5717 (1999) and others), realization of the magnetoresistance ratioof 100% is not impossible.

However, CPP type elements having been heretofore reported mainly useartificial lattices, and a large total thickness of films and a largenumber of boundary faces caused a large variation of resistance(absolute output value). To realize a satisfactory magnetic propertyrequired for a head, the use of a spin valve structure is desirable.

FIG. 30 is a cross-sectional view that schematically showing a CPP typemagnetoresistance effect element having a spin valve structure. Amagnetoresistance effect film M is interposed between an upper electrode52 and a lower electrode 54, and a sense current flows perpendicularlyto the film plane. The magnetoresistance effect film M shown here hasthe basic film structure sequentially made by depositing a base layer12, antiferromagnetic layer 14, magnetization-pinned layer 16,nonmagnetic intermediate layer 18, magnetization free layer 20 andprotective layer 22 on the lower electrode 54.

As these layers are basically made of metals. The magnetization-pinnedlayer (called pinned layer) is a magnetic layer in which magnetizationis fixed substantially in one direction. The magnetization free layer 20(called free layer) is a magnetic layer in which the direction ofmagnetization can freely change depending upon an external magneticfield.

This kind of spin valve structure, however, has a smaller totalthickness and fewer boundary faces than those of artificial lattices.Therefore, if a current is supplied perpendicularly to the film plane,then the resistance becomes small and the absolute output value becomessmaller.

For example, if a spin valve film having a film structure heretoforeused in a CIP structure is directly used in a CPP structure and acurrent is supplied perpendicularly of the film plane, the absolutevalue of the output per 1 μm², AΔR, is only about 1 mΩμm². That is, forpractically using a CPP using a spin valve film, increase of the outputis an important issue. For this purpose, it is very effective toincrease the resistance value of a portion of the magnetoresistanceeffect element taking part in spin-dependent conduction and therebyincrease the resistance change.

SUMMARY OF THE INVENTION

Output of a CPP type magnetoresistance effect element is determined byspin-dependent scattering along the interface between a magnetic layerand a nonmagnetic layer (interface scattering) and spin-dependentscattering in the magnetic layer (bulk scattering). Taking it intoaccount, a large output increase can be expected by using a materialexhibiting large spin-dependent interface scattering to form theinterface with the nonmagnetic layer and using a material exhibitinglarge spin-dependent bulk scattering to form the substantial partoccupying the majority part of the magnetic layer.

If a nonmagnetic back layer is inserted along one of interfaces of themagnetically pinned layer or magnetically free layer not contacting thenonmagnetic intermediate layer, spin-dependent interface scatteringalong the interface between the pinned layer and the nonmagnetic backlayer or the interface between the free layer and the nonmagnetic backlayer can be used. Thus, if a material exhibiting large spin-dependentinterface scattering is used to form the interface between the pinnedlayer and the nonmagnetic back layer or between the free layer and thenonmagnetic back layer, the output increases.

Insertion of a different material in a location within the pinned layeror the free layer results in bringing a modulation in the bandstructure, and it may possibly increase the output.

The Inventors proceeded with their own trial and researches from thatpoint of view, and reached the invention of the unique magnetoresistanceeffect element explained below.

According to the embodiment of the invention, there is provided amagnetoresistance effect element comprising:

a magnetoresistance effect film including a magnetically pinned layerhaving a magnetic material film whose direction of magnetization ispinned substantially in one direction, a magnetically free layer havinga magnetic material film whose direction of magnetization changes inresponse to an external magnetic field, and a nonmagnetic metalintermediate layer located between said pinned layer and said freelayer; and

a pair of electrodes electrically connected to said magnetoresistanceeffect film to supply a sense current perpendicularly to a film plane ofsaid magnetoresistance effect film,

at least one of said pinned layer and said free layer including athin-film insertion layer.

The thin-film insertion layer may be made of an alloy containing atleast two kinds of metals among iron (Fe), cobalt (Co) and nickel (Ni)as matrix elements thereof, and in case of a binary alloy, said alloycontaining each of said two kinds of matrix elements by not less than 25atomic % respectively, and in case of a ternary alloy, said alloycontaining each of said three kinds of matrix elements by not less than5 atomic % respectively.

The thin-film insertion layer may alternatively be made of a binaryalloy or a ternary alloy containing at least two kinds of metals amongiron (Fe), cobalt (Co) and nickel (Ni) as matrix elements thereof, andadditionally containing a quantity of at least one kind of elementselected from the group consisting of chromium (Cr), vanadium (V),tantalum (Ta), niobium (Nb), scandium (Sc), titanium (Ti), manganese(Mn), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium(Zr), hafnium (Hf, yttrium (Y), technetium (Tc), rhenium (Re), ruthenium(Ru), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver(Ag), gold (Au), boron (B), aluminum (Al), indium (In), carbon (C),silicon (Si), tin (Sn), calcium (Ca), strontium (Sr), barium (Ba),oxygen (O), nitrogen (N) and fluorine (F) not less than 0.1 atomic % andnot exceeding 30 atomic %.

The thin-film insertion layer may alternatively be a binary alloycontaining a quantity of iron (Fe) not less than 50 atomic % as themajor component thereof, or a ternary alloy containing a quantity ofiron (Fe) not less than 25 atomic % as the major component thereof, andsaid alloy having a body-centered cubic crystal structure.

The thin-film insertion layer may alternatively be made of iron (Fe)having a body-centered cubic crystal structure.

The thin-film insertion layer may alternatively be made of an alloycontaining iron (Fe) and chromium (Cr) as major components thereof andadjusted in quantity of chromium (Cr) in the range from 0 atomic % to 80atomic %, said alloy having a body-centered cubic crystal structure.

The thin-film insertion layer may alternatively be made of an alloycontaining iron (Fe) and vanadium (V) as major components thereof andadjusted in quantity of vanadium (V) in the range from 0 atomic % to 70atomic %, said alloy having a body-centered cubic crystal structure.

The thin-film insertion layer may alternatively be made of iron (Fe), ora binary or ternary alloy of iron (Fe), cobalt (Co) and nickel (Ni)containing a quantity of iron (Fe) not less than 50 atomic % in case ofsaid binary alloy or 25% atomic % in case of said ternary alloy, andadditionally containing a quantity of at least one kind of elementselected from the group consisting of chromium (Cr), vanadium (V),tantalum (Ta), niobium (Nb), scandium (Sc), titanium (Ti), manganese(Mn), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium(Zr), hafnium (Hf, yttrium (Y), technetium (Tc), rhenium (Re), ruthenium(Ru), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver(Ag), gold (Au), boron (B), aluminum (Al), indium (In), carbon (C),silicon (Si), tin (Sn), calcium (Ca), strontium (Sr), barium (Ba),oxygen (O), nitrogen (N) and fluorine (F) not less than 0.1 atomic % andnot exceeding 30 atomic %.

The thin-film insertion layer may alternatively be made of cobalt (Co),or a binary or ternary alloy of iron (Fe), cobalt (Co) and nickel (Ni)containing a quantity of cobalt (Co) not less than 50 atomic % in caseof said binary alloy or 25% atomic % in case of said ternary alloy, andadditionally containing a quantity of at least one kind of elementselected from the group consisting of chromium (Cr), vanadium M,tantalum (Ta), niobium (Nb), scandium (Sc), titanium (Ti), manganese(Mn), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium(Zr), hafnium (Hf, yttrium (Y), technetium (Tc), rhenium (Re), ruthenium(Ru), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver(Ag), gold (Au), boron (B), aluminum (Al), indium (In), carbon (C),silicon (Si), tin (Sn), calcium (Ca), strontium (Sr), barium (Ba),oxygen (O), nitrogen (N) and fluorine (F) not less than 0.1 atomic % andnot exceeding 30 atomic %.

The thin-film insertion layer may alternatively be made of nickel (Ni),or a binary or ternary alloy of iron (Fe), cobalt (Co) and nickel (Ni)containing a quantity of nickel (Ni) not less than 50 atomic % in caseof said binary alloy or 25% atomic % in case of said ternary alloy, andadditionally containing a quantity of at least one kind of elementselected from the group consisting of chromium (Cr), vanadium (V),tantalum (Ta), niobium (Nb), scandium (Sc), titanium (Ti), manganese(Mn), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium(Zr), hafnium (Hf, yttrium (Y), technetium (Tc), rhenium (Re), ruthenium(Ru), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver(Ag), gold (Au), boron (B), aluminum (Al), indium (In), carbon (C),silicon (Si), tin (Sn), calcium (Ca), strontium (Sr), barium (Ba),oxygen (O), nitrogen (N) and fluorine (F) not less than 0.1 atomic % andnot exceeding 30 atomic %.

The thin-film insertion layer may alternatively be made of a iron(Fe)-cobalt (Co)-system alloy having a body-centered cubic crystalstructure, and additionally containing a quantity of at least one kindof element selected from the group consisting of chromium (Cr), vanadium(V), tantalum (Ta), niobium (Nb), scandium (Sc), titanium (Ti),manganese (Mn), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge),zirconium (Zr), hafnium (Hfl, yttrium (y), technetium (Tc), rhenium(Re), ruthenium (Ru), rhodium (Rh), iridium (Ir), palladium (Pd),platinum (Pt), silver (Ag), gold (Au), boron (B), aluminum (Al), indium(In), carbon (C), silicon (Si), tin (Sn), calcium (Ca), strontium (Sr),barium (Ba), oxygen (O), nitrogen (N) and fluorine (F) not less than 0.1atomic % and not exceeding 10 atomic %.

The thin-film insertion layer may alternatively be made of a iron(Fe)-cobalt (Co)-system alloy having a body-centered cubic crystalstructure, and layers made of at least one kind of element selected fromthe group consisting of chromium (Cr), vanadium (V), tantalum (Ta),niobium (Nb), scandium (Sc), titanium (Ti), manganese (Mn), copper (Cu),zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), hafnium (Hf),yttrium (Y), technetium (Tc), rhenium (Re), ruthenium (Ru), rhodium(Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver (Ag), gold(Au), boron (B), aluminum (Al), indium (In), carbon (C), silicon (Si),tin (Sn), calcium (Ca), strontium (Sr), barium (Ba), oxygen (O),nitrogen (N) and fluorine (F) having a thickness not thinner than 0.03nm and not exceeding 1 nm which permits said layers to exist as abody-centered cubic structure being periodically inserted in said alloy.

The nonmagnetic metal intermediate layer may have a resistance adjustinglayer including at least one of oxides, nitrides and fluorides, and thethin-film insertion layer may include at least one element selected fromthe group consisting of iron (Fe), cobalt (Co) and nickel (Ni).

At least one of the pinned layer and said free layer may have aresistance adjusting layer including at least one of oxides, nitridesand fluorides, and the thin-film insertion layer may include at leastone element selected from the group consisting of iron (Fe), cobalt (Co)and nickel (Ni).

A magnetic head according to the embodiment of the invention maycomprise a magnetoresistance effect element having any one of theabove-mentioned features.

A magnetic reproducing apparatus which reads information magneticallyrecorded in a magnetic recording medium according to the embodiment ofthe invention may comprise a magnetoresistance effect element having anyone of the above-mentioned features.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given herebelow and from the accompanying drawings of theembodiments of the invention. However, the drawings are not intended toimply limitation of the invention to a specific embodiment, but are forexplanation and understanding only.

In the drawings:

FIG. 1 is a diagram that schematically illustrates a cross-sectionalstructure of the substantial part of the magnetoresistance effectelement according to an embodiment of the invention;

FIG. 2 is a diagram that schematically illustrates the second specificexample of the magnetoresistance effect element according to anembodiment of the invention;

FIG. 3 is a diagram that schematically illustrates the third specificexample of the magnetoresistance effect element according to anembodiment of the invention;

FIG. 4 is a diagram that schematically illustrates the fourth specificexample of the magnetoresistance effect element according to anembodiment of the invention;

FIG. 5 is a diagram that schematically illustrates the fifth specificexample of the magnetoresistance effect element according to anembodiment of the invention;

FIG. 6 is a graph diagram that shows dependency of the resistance changeupon the thickness of a thin-film insertion layer CO₅₀Fe₅₀;

FIG. 7 is a graph diagram that shows dependency of the coercive force ofthe free layer upon thickness of the thin-film insertion layer;

FIG. 8 is a graph diagram that shows dependency of the resistance changeupon the thickness of the thin-film insertion layer CO₅₀Fe₅₀;

FIG. 9 is a graph diagram that shows dependency of the coercive force ofthe free layer upon thickness of the thin-film insertion layer;

FIG. 10 is a graph diagram that shows dependency of the resistancechange upon the thickness of the thin-film insertion layer CO₅₀Fe₅₀;

FIG. 11 is a graph diagram that shows dependency of the coercive forceof the free layer upon thickness of the thin-film insertion layer;

FIG. 12 is a graph diagram that shows dependency of the resistancechange upon the thickness of the thin-film insertion layer Co₅₀Fe₅₀;

FIG. 13 is a graph diagram that shows dependency of the coercive forceof the free layer upon thickness of the thin-film insertion layer;

FIG. 14 is a diagram that schematically shows a structure having a backinsertion layer 36 experimentally prepared as the sixteenth embodimentof the invention;

FIG. 15 is a diagram that schematically shows a structure locating ananti-ferromagnetic layer 14 in an upper position;

FIG. 16 is a diagram that schematically shows a structure inserting athin-film insertion layer 32 between a pinned layer 16 and theanti-ferromagnetic layer 14;

FIG. 17 is a diagram that schematically showing a structure insertingthe thin-film insertion layer 32 inside the pinned layer 16;

FIG. 18 is a diagram that schematically shows a structure inserting thethin-film insertion layer 32 between the pinned layer 16 and anonmagnetic intermediate layer 18;

FIG. 19 is a diagram that schematically shows a structure inserting thethin-film insertion layer 34 between the nonmagnetic intermediate layer18 and the free layer 20;

FIG. 20 is a diagram that schematically shows a structure inserting thethin-film insertion layer 34 inside the free layer 20;

FIG. 21 is a diagram that schematically shows a structure inserting thethin-film insertion layer 34 between the free layer 20 and the backinsertion layer 36;

FIG. 22 is a diagram that schematically shows another specific exampleof the cross-sectional structure of a magnetoresistance effect elementhaving a multi-layered ferri-structure;

FIG. 23 is a diagram that schematically shows a cross-sectionalstructure of a magnetoresistance effect element having a resistanceadjusting layer;

FIG. 24 is a diagram that schematically shows a cross-sectionalstructure of a magnetoresistance effect element having a resistanceadjusting layer;

FIG. 25 is a diagram that schematically shows a cross-sectionalstructure of a dual type magnetoresistance effect element;

FIG. 26 is a perspective view that shows general configuration of thesubstantial part of a magnetoresistance effect element according to anembodiment of the invention;

FIG. 27 is an enlarged, perspective view of a distal end from anactuator arm 155 of a magnetic head assembly;

FIG. 28 is a diagram that schematically shows a CPP element structureexperimentally prepared according to an embodiment of the invention;

FIG. 29 is a diagram that schematically shows another CPP elementstructure experimentally prepared according to an embodiment of theinvention; and

FIG. 30 is a cross-sectional view that schematically shows a CPP typemagnetoresistance effect element having a spin valve structure.

DETAILED DESCRIPTION OF THE INVENTION

Some embodiments of the invention will be explained below with referenceto the drawings.

FIG. 1 is a diagram that schematically illustrates a cross-sectionalstructure of the substantial part of the magnetoresistance effectelement according to an embodiment of the invention. Themagnetoresistance effect element shown here has a structure including abase layer 12, anti-ferromagnetic layer 14, magnetically pinned layer16, nonmagnetic intermediate layer 18, magnetically free layer 20,protective layer 22 and upper electrode 52 that are sequentiallydeposited in this order on a lower electrode 54. That is, themagnetoresistance effect film is sandwiched between the upper electrode52 and the lower electrode 54, and the sense current flowsperpendicularly to the film plane.

It is the portion of the pinned layer 16/nonmagnetic intermediate layer18/free layer 20 that works for the magnetoresistance effect in theillustrated magnetoresistance effect element.

More specifically, in that portion, a resistance depending upon spins isgenerated against spin-polarized electrons, and the spin-dependentresistance is generated. According to the embodiment of the invention,as explained in greater detail, by inserting thin-film insertion layers32 and 34 of unique materials in the pinned layer 16 and the free layer20 and thereby enhancing the output of the element, i.e. the absolutevalue of the magnetoresistance change, it is possible to realize a CPPtype magnetoresistance effect element acceptable for practical use.

That is, output of a CPP element is determined by spin-dependentscattering along the interface between a magnetic layer and anonmagnetic layer (interface scattering) and spin-dependent scatteringin the magnetic layer (bulk scattering). Thus a large output increasecan be expected by using a material exhibiting large spin-dependentinterface scattering to form the interface with the nonmagnetic layerand using a material exhibiting large spin-dependent bulk scattering toform the substantial part occupying the majority part of the magneticlayer.

Through their own trials and reviews, the Inventors have got theknowledge that a thin-film insertion layer of a unique material insertedas a part of the pinned layer 16 and/or free layer 20 contributes topromoting those spin-dependent scatterings and to increasing themagnetoresistance change.

While postponing explanation of the thin-film insertion layersparticularly employed in the embodiment of the invention for laterdetailed explanation in conjunction with examples, here is made anexplanation about other components forming the magnetoresistance effectelement according to the embodiment.

The base layer 12 is preferably made of a material functioning toimprove crystalline properties of the overlying free layer 20 and pinnedlayer 16 and to enhance the smoothness of the interfaces. A materialhaving this kind of nature is, for example, an alloy of Ni (nickel), Fe(iron) and Cr (chromium) containing approximately 40% of Cr. Althoughnot shown, for higher-quality alignment, a layer made of NiFe, Ru(ruthenium), Cu (copper), etc. for example, may be inserted between thebase layer 12 and the anti-ferromagnetic layer 14.

The anti-ferromagnetic layer 14 has the role of pinning magnetization ofthe pinned layer 16. That is, by locating the anti-ferromagnetic layer14 of PtMn (platinum manganese), IrMn (iridium manganese), PdPtMn(palladium platinum manganese) or NiMn, for example, next to the pinnedlayer 16, magnetization of the pinned layer 16 can be pinned in onedirection by making use of an exchanging coupling bias magnetic fieldgenerated along the interface.

To enhance the magnetically pinning effect of the pinned layer 16, amagnetic coupling intermediate layer (not shown) is preferably insertedbetween the anti-ferromagnetic layer 14 and the pinned layer 16.Material of the magnetic coupling intermediate layer may be aferromagnetic alloy containing Fe, Co (cobalt) or Ni, for example, asits major component. Thickness thereof should be as thin as 0.1 through3 nm to control magnetization of the pinned layer 16.

As the magnetic coupling intermediate layer, a so-called synthetic typemulti-layered structure made of a multi-layered ferri-type film of aferromagnetic layer/anti-parallel coupling layer/ferromagnetic layeremployed in spin-valve GMR is also preferable for controlling pinningmagnetization.

The nonmagnetic intermediate layer 18 has the role of interruptingmagnetic coupling between the pinned layer 16 and the free layer 20.Further, the nonmagnetic intermediate layer 18 preferably functions toform a high-quality interface between the nonmagnetic intermediate layer18 and the pinned layer 16 (thin-film insertion layer 32) such thatup-spin electrons flowing from the pinned layer 16 to the free layer 20are not scattered.

Material of the nonmagnetic intermediate layer 18 may be, for example,Cu (copper), Au (gold), Ag (silver), Ru (ruthenium), Ir (iridium), Pd(palladium), Cr (chromium), Mg (magnesium), Al (aluminum), Rh (rhodium)or Pt (platinum). Thickness thereof should be thick enough tosufficiently interrupt magnetic coupling between the free layer 20 andthe pinned layer 16 and thin enough to prevent scattering of up-spinelectrons from the pinned layer 16. Preferably, the thickness is in therange from 0.5 to 5 nm, approximately, although it depends on thematerial used.

The protective layer 22 has the role of protect the multi-layeredstructure of the magnetoresistance effect film during patterning and/orother processing.

In the CPP magnetoresistance effect element having those components, themagnetoresistance change can be increased by inserting the thin-filminsertion layer 32 as a part of the pinned layer 16 and the thin-filminsertion layer 34 as a part of the free layer 20 as shown in FIG. 1.

Before explaining specific configuration of the thin-film insertionlayers 32, 34, other specific examples of magnetoresistance effectelements employable in the embodiment of the invention are explainedbelow.

FIGS. 2 through 5 are diagrams that schematically illustrate those otherspecific examples of magnetoresistance effect elements according to theembodiment of the invention. In these drawings, the same or equivalentcomponents to those shown in FIG. 1 are labeled with common referencenumerals, and their detailed explanation is omitted.

The magnetoresistance effect element shown in FIG. 2 is a modificationin the stacking order from the element of FIG. 1. Also in this element,by inserting the thin-film insertion layer 32 as the interface betweenthe pinned layer 16 and the nonmagnetic intermediate layer 18 andinserting the thin-film insertion layer 34 as the interface between thefree layer 20 and the nonmagnetic intermediate layer 18, the sameeffects as those already explained in conjunction with FIG. 1 can beobtained.

In case of the magnetoresistance effect element shown in FIG. 3, bydividing the pinned layer by an anti-ferromagnetic coupling layer 40 andpinning the directions of magnetization in the first pinned layer 16Aand the second pinned layer 16B, thereby to reduce magnetization of thewhole pinned layer, the magnetically pinning force by theanti-ferromagnetic layer 14 can be increased.

Also in the element shown in FIG. 3, by inserting the thin-filminsertion layers 32, 34 in the pinned layer 16 and the free layer 20,respectively, the above-explained spin-scattering effect is obtained.

In case of the magnetoresistance effect element shown in FIG. 4, each ofthe thin-film insertion layers 32, 34 has a multi-layered structurealternately depositing ferromagnetic layers F and nonmagnetic layers N.

On the other hand, in case of the magnetoresistance effect element showin FIG. 5, each of the thin-film insertion layers 32, 34 has amulti-layered structure alternately depositing two different kinds offerromagnetic layers F1, F2.

Effects of the embodiment of the invention were confirmed by way of thefollowing two elements.

One of them has a CPP element structure as shown in FIG. 28. Structureof this element is explained below, following to its manufacturingprocess.

First, AlO_(x) is deposited on a Si (silicon) substrate (not shown) toform a 500 nm thick layer, and a resist is once coated thereon andselectively removed from the region for the lower electrode 54 by PEP(photoengraving process).

After that, AlO_(x) is selectively removed from the region not coated bythe resist by RIE (reactive ion etching), and the lower electrode isformed as a Ta (5 nm)/Cu (400 nm)/Ta (20 nm) film. Numerals in theparentheses indicate thicknesses (also in the description to follow).

Thereafter, CMP (chemical mechanical polishing) is carrier out to exposeAlO_(x) in the region other than the region for the lower electrode. Onsuch a structure, a magnetoresistance effect film M sized 3×3 μm²through 5×5 μm² was formed. In some elements, a hard film 60 of CoPt wasformed on the side surface of the magnetoresistance effect film up to 30nm.

A 200 nm thick SiO_(x) was formed as a passivation film 70, and acontact hole (0.3 μmφ-3 μmφ) was formed in a central position of themagnetoresistance effect film M by RIE and ion milling.

Subsequently, the upper electrode 52 (Ta(5 nm)/Cu (400 nm)/Ta (5 nm))and an electrode pad (Au (200 nm)) were formed.

The other of those two elements has a structure as shown in FIG. 29. Thesame process was used up to deposition of the lower electrode 54 andCMP. Thereafter, the magnetoresistance effect film M was formed on thestructure, and the lengthwise direction was regulated from 2 μm to 5 μm.

Then, SiO_(x) to be used as the passivation film 70 was deposited up to200 nm, and the size was regulated from 1.5 μm to 5 μm in the directionangled by 90 degrees from the lengthwise direction. In this case, a 100nm Au film was formed just above the magnetoresistance effect film M toensure a uniform flow of the sense current throughout themagnetoresistance effect film M, and the upper electrode 52 and theelectrode pad were formed thereafter in the same manner as the firstelement.

With these elements, their magnetoresistance properties were measured bythe four-terminal method, and they were confirmed to be equivalent inoutput. Further, their crystalline structures were analyzed by usingCu—K α rays, their morphologies were confirmed by cross-sectional TEM(transmission electron microscopy), and their composition profiles werereviewed by n-EDX (energy dispersive X-ray spectroscopy). Additionally,EXAFS (extended X-ray absorption fine structure) electron states wereinvestigated for specific elements in the alloys.

Explained below is a result of investigation about appropriatethicknesses of the thin-film insertion layers 32, 34 to be insertedbetween the pinned layer 16 or the free layer 20 and the nonmagneticintermediate layer 18 in the first to fourth examples of the invention.

FIRST EXAMPLE

In the structure shown in FIG. 1, a magnetoresistance effect filmincluding the free layer 20 and the pinned layer 16 each being an alloylayer of a Ni₅₀Fe₂₀ layer and a Co₅₀Fe₅₀ thin-film insertion layer wasformed. The film configuration is as follows.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Ni₈₀Fe₂₀ (5-xnm) Thin-film insertion layer 34: Co₅₀Fe₅₀ (x nm) Nonmagneticintermediate layer 18: Cu (3 nm) Thin-film insertion layer 32: Co₅₀Fe₅₀(x nm) Part of the pinned layer 16: Ni₈₀Fe₂₀ (5-x nm) Anti-ferromagneticlayer 14: PtMn (15 nm) Second base layer 12: NiFeCr (5 nm) First baselayer 12: Ta (5 nm)

A plurality of such elements were prepared by fixing the total thicknessof the free layer 20 and the pinned layer 16 in 5 nm and changing thethickness x of the Co₅₀Fe₅₀ layer as the thin-film insertion layer from0 nm to 5 nm in each prepared element. Additionally, thickness of thethin-film insertion layer 32 inserted in the pinned layer 16 andthickness of the thin-film insertion layer 34 inserted in the free layer20 were equally x nm.

FIG. 6 is a graph diagram that shows dependency of the resistance changeupon the thickness of a thin-film insertion layer Co₅₀Fe₅₀. The abscissashows thickness of the thin-film insertion layer, and the ordinate showsthe quantity of resistance change AΔR per unit area 1 μm² of theelement.

It is appreciated from the graph that, when the thin-film insertionlayer is thickened, AΔR begins to increase from near the thickness of0.5 nm, then becomes approximately 1.4 times when the thickness is 1 nm,and even thereafter increases continuously. In case the thin-filminsertion layer is excessively thin, it is presumed that the desiredquality of the Co₅₀Fe₅₀ thin-film insertion layer will not be formed dueto mixing (alloying) and the output will not increase. Therefore, incase an element of a clean film quality free from mixing, the thin-filminsertion layer, even thinner, will be also effective.

It is presumed that the increase of AΔR obtained with such a smallthickness of the thin-film insertion film is caused by an increase ofthe spin-dependent interface scattering. However, because Co₅₀Fe₅₀ islarge also in spin-dependent bulk scattering, it is appreciated that theoutput further increases when its thickness increases.

FIG. 7 is a graph diagram that shows dependency of the coercive force ofthe free layer upon thickness of the thin-film insertion layer. Theabscissa shows the thickness of the thin-film insertion layer, and theordinate shows the coercive force Hc of the free layer.

It is appreciated from FIG. 7 that the coercive force Hc increases asthe thin-film insertion layer if made thicker, and exceeds 15 Oe(oersteds) when it reaches 1 nm. When the coercive force of the freelayer increases, the sensitivity to the external magnetic fielddegrades. Therefore, there is an upper limit for the thickness of thethin-film insertion layer.

Taking these factors into account, in case the free layer and the pinnedlayer are symmetrically formed, that is, in case the free layer 20 andthe pinned layer 16 are alloy layers each made up of the Ni₈₀Fe₂₀ layerand the Co₅₀Fe₅₀ thin-film insertion layer, and thickness of thethin-film insertion layer is equal in both layers 20 and 16, practicalthickness will be from 0.5 nm to 1 nm for both thin-film insertionlayers 32, 34 from the viewpoint of increasing AΔR and controlling Hc.

SECOND EXAMPLE

As the second example of the embodiment of the invention, amagnetoresistance effect film including the free layer 20 and the pinnedlayer 16 each being an alloy layer of a Ni₈₀Fe₂₀ layer and a Co₅₀Fe₅₀thin-film insertion layer was formed in the structure shown in FIG. 1.The film configuration is as follows.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (5-xnm) Thin-film insertion layer 34: Co₅₀Fe₅₀ (x nm) Nonmagneticintermediate layer 18: Cu (3 nm) Thin-film insertion layer 32: Co₅₀Fe₅₀(x nm) Part of the pinned layer 16: Co₉₀Fe₁₀ (5-x nm) Anti-ferromagneticlayer 14: PtMn (15 nm) Second base layer 12: NiFeCr (5 nm) First baselayer 12: Ta (5 nm)

Here again, a plurality of such elements were prepared by fixing thethickness of the free layer 20 and the pinned layer 16 in 5 nm andchanging the thickness of the Co₅₀Fe₅₀ thin-film insertion layers 32, 34from 0 nm to 5 nm in each prepared element.

FIG. 8 is a graph diagram that shows dependency of the resistance changeupon the thickness of the thin-film insertion layer Co₅₀Fe₅₀. Theabscissa shows thickness of the thin-film insertion layer, and theordinate shows the quantity of resistance change AΔR per unit area 1 μm²of the element.

It is appreciated from the graph that, when the thin-film insertionlayer is thickened, AΔR begins to increase from the thickness of 0.5 nm,then becomes approximately 1.5 times when the thickness is 1 nm, andeven thereafter increases continuously. Again, in case the thin-filminsertion layer is excessively thin, it is presumed that the desiredquality of the Co₅₀Fe₅₀ thin-film insertion layer will not be formed dueto mixing (alloying) and the output will not increase. Therefore, incase an element of a clean film quality free from mixing, the thin-filminsertion layer, even thinner, will be also effective.

It is presumed that the increase of AΔR obtained with such a smallthickness of the thin-film insertion film is caused by an increase ofthe spin-dependent interface scattering. However, because Co₅₀Fe₅₀ islarge also in spin-dependent bulk scattering, it is appreciated that theoutput further increases when its thickness increases.

FIG. 9 is a graph diagram that shows dependency of the coercive force ofthe free layer upon thickness of the thin-film insertion layer. Theabscissa shows the thickness of the thin-film insertion layer, and theordinate shows the coercive force Hc of the free layer.

It is appreciated from FIG. 9 that the coercive force Hc increases asthe thin-film insertion layer if made thicker, and exceeds 15 Oe(oersteds) when it reaches 0.75 nm. When the coercive force of the freelayer increases, the sensitivity to the external magnetic fielddegrades. Therefore, there is an upper limit for the thickness of thethin-film insertion layer.

Here again, taking these factors into account, in case the free layerand the pinned layer are symmetrically formed, that is, in case the freelayer 20 and the pinned layer 16 are alloy layers each made up of theCo₉₀Fe₁₀ layer and the Co₅₀Fe₅₀ thin-film insertion layer, and thicknessof the thin-film insertion layer is equal in both layers 20 and 16,practical thickness will be from 0.5 nm to 0.75 nm for both thin-filminsertion layers 32, 34 from the viewpoint of increasing AΔR andcontrolling Hc.

THIRD EXAMPLE

As the third example of the embodiment of the invention, amagnetoresistance effect film was formed in which the free layer 20 is a5 nm thick Ni₅₀Fe₂₀ layer without insertion of the thin-film insertionlayer 34 and only the pinned layer 16 is made up of the Ni₅₀Fe₂₀ layerand the Co₅₀Fe₅₀ thin-film insertion layer in the structure shown inFIG. 1. The film configuration is as follows.

Protective layer 22: Ta (10 nm) Free layer 20: Ni₈₀Fe₂₀ (5 nm)Nonmagnetic intermediate layer 18: Cu (3 nm) Thin-film insertion layer32: Co₅₀Fe₅₀ (x nm) Part of the pinned layer 16: Ni₈₀Fe₂₀ (5-x nm)Anti-ferromagnetic layer 14: PtMn (15 nm) Second base layer 12: NiFeCr(5 nm) First base layer 12: Ta (5 nm)

Here again, a plurality of such elements were prepared by fixing thethickness of the pinned layer 16 in 5 nm and changing the thickness ofthe Co₅₀Fe₅₀ thin-film insertion layer 32 from 0 nm to 5 nm in eachprepared element.

FIG. 10 is a graph diagram that shows dependency of the resistancechange upon the thickness of the thin-film insertion layer Co₅₀Fe₅₀. Theabscissa shows thickness of the thin-film insertion layer, and theordinate shows the quantity of resistance change AΔR per unit area 1 μm²of the element.

It is appreciated from the graph that, when the thin-film insertionlayer is thickened, AΔR begins to increase from the thickness of 0.75 nmand becomes approximately 1.6 times when the thickness reaches 5 nm tofully replace the pinned layer 16. Here again, in case the thin-filminsertion layer is excessively thin, it is presumed that the desiredquality of the Co₅₀Fe₅₀ thin-film insertion layer will not be formed dueto mixing (alloying) and the output will not increase. Therefore, incase an element of a clean film quality free from mixing, the thin-filminsertion layer, even thinner, will be also effective.

It is presumed that the increase of AΔR obtained with such a smallthickness of the thin-film insertion film is caused by an increase ofthe spin-dependent interface scattering. However, because Co₅₀Fe₅₀ islarge also in spin-dependent bulk scattering, it is appreciated that theoutput further increases when its thickness increases.

FIG. 11 is a graph diagram that shows dependency of the coercive forceof the free layer upon thickness of the thin-film insertion layer. Theabscissa shows the thickness of the thin-film insertion layer, and theordinate shows the coercive force Hc of the free layer.

When the thin-film insertion layer is inserted only in the pinned layer16, Hc is suppressed as compared with the structure the thin-filminsertion layer is inserted in both the pinned layer and the free layer.However, when its thickness reaches 5 nm where the spin valve filmentirely begins to deteriorate in crystalline property, Hc undesirablyexceeds 10 Oe.

Therefore, in case the thin-film insertion layer 32 made of Co₅₀Fe₅₀ isinserted only in the pinned layer, it will be practical to limit thethickness of the thin-film insertion layer 32 in the range not thinnerthan 0.75 nm and not thicker than 4 nm from the viewpoint of increasingAΔR and controlling Hc.

FOURTH EXAMPLE

As the fourth example of the embodiment of the invention, amagnetoresistance effect film was formed in which the pinned layer 16has the fixed structure of Ni₈₀Fe₂₀ (2 nm)/Co₅₀Fe₅₀ (3 nm) while thefree layer 20 is made up of a Ni₈₀Fe₂₀ layer and a Co₉₀Fe₁₀ thin-filminsertion layer 20 inserted therein in the structure shown in FIG. 1.The film configuration is as follows.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Ni₈₀Fe₂₀ (5-xnm) Thin-film insertion layer 34: Co₉₀Fe₁₀ (x nm) Nonmagneticintermediate layer 18: Cu (3 nm) Pinned layer 16: Co₅₀Fe₅₀ (3 nm) Pinnedlayer 16: Ni₈₀Fe₂₀ (2 nm) Anti-ferromagnetic layer 14: PtMn (15 nm)Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

In this example, a plurality of elements were prepared by fixing thetotal thickness of the free layer 20 in 5 nm and changing the thicknessof the Co₉₀Fe₁₀ thin-film insertion layer 34 from 0 nm to 5 nm in eachprepared element.

FIG. 12 is a graph diagram that shows dependency of the resistancechange upon the thickness of the thin-film insertion layer Co₉₀Fe₁₀. Theabscissa shows thickness of the thin-film insertion layer, and theordinate shows the quantity of resistance change AΔR per unit area 1 μm²of the element.

It is appreciated from the graph that, when the thin-film insertionlayer is thickened, AΔR begins to increase from the thickness of 0.25 nmand reaches the maximum value when the thickness is 2 nm. Here again, incase the thin-film insertion layer is excessively thin, it is presumedthat the desired quality of the Co₉₀Fe₁₀ thin-film insertion layer willnot be formed due to mixing (alloying) and the output will not increase.Therefore, in case an element of a clean film quality free from mixing,the thin-film insertion layer, even thinner, will be also effective.

Although the Co₉₀Fe₁₀ thin-film is greatly effective for enhancing thespin-dependent interface scattering, Ni₅₀Fe₂₀ is superior inspin-dependent bulk scattering. Therefore, if the thin-film insertionlayer 34 is thickened, the output tends to decrease.

FIG. 13 is a graph diagram that shows dependency of the coercive forceof the free layer upon thickness of the thin-film insertion layer. Theabscissa shows the thickness of the thin-film insertion layer, and theordinate shows the coercive force Hc of the free layer.

As the thin-film insertion layer 34 becomes thicker, Hc increases.However, this tendency is moderate, and limited within 10 Oe as a whole.

Therefore, in case the pinned layer 16 is fixed as Ni₈₀Fe₂₀ (2nm)/Co₅₀Fe₅₀ (3 nm) and the Co₉₀Fe₁₀ thin-film insertion layer isinserted in the free layer 20, it will be practical to limit thethickness of the thin-film insertion layer 34 in the range not smallerthan 0.25 nm and smaller than 2.5 nm from the viewpoint of increasingAΔR and controlling Hc.

Hereafter, a result of investigation about appropriate materials of thethin-film insertion layers to be inserted in the pinned layer and thefree layer 20 as the fifth to eleventh examples of the invention.

FIFTH EXAMPLE

As the fifth example, magnetoresistance effect elements shown in FIG. 1were prepared. Their film configuration is as follows.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (2 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As the material X of the thin-film insertion layers 32, 34, five kindsof Fe—Co-system alloys (Co, Co₉₀Fe₁₀, Fe₅₀Co₅₀, Fe₈₀Co₂₀ and Fe),respectively. Relations between the materials of the thin-film insertionlayers 32, 34 and AΔR obtained thereby are shown below.

X: AΔR (mΩμm²) Co: 0.6 Co₉₀Fe₁₀: 0.8 Fe₅₀Co₅₀: 1.55 Fe₈₀Co₂₀: 1.45 Fe:1.35

Note here that, in case the composition X is Co₉₀Fe₁₀, it is the samecomposition as that of the other portions of the pinned layer 16 and thefree layer 20, and these other portions are not distinctive from thethin-film insertion layers 32, 34. It has been found from the aboveresult that, in case such Fe—Co-system alloys are used as materials ofthe thin-film insertion layers 32, 34, the use of Fe₅₀Co₅₀, Fe₈₀Co₂₀ andFe whose crystal structures are body-centered cubic crystals iseffective to increase AΔR. In contrast, the use of Co has been found todecrease AΔR from the value before the insertion.

Therefore, if Fe—Co-system alloys are used as materials of the thin-filminsertion layers 32, 34, those having compositions making body-centeredcubic crystal structures are preferably selected.

SIXTH EXAMPLE

As the sixth example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (2 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As the material X of the thin-film insertion layers 32, 34, five kindsof Fe—Ni-system alloys (Ni, Ni₈₀Fe₂₀, Ni₅₀Fe₅₀, Fe₉₀Ni₁₀ and Fe),respectively. Relations between the materials of the thin-film insertionlayers 32, 34 and AΔR obtained thereby are shown below.

X: AΔR (mΩμm²) Not inserted: 0.8 Ni: 0.3 Ni₈₀Fe₂₀: 0.4 Ni₅₀Fe₅₀: 0.9Fe₉₀Ni₁₀: 1.3 Fe: 1.35

It has been found from the above result that, also in case suchFe—Ni-system alloys are used as materials of the thin-film insertionlayers 32, 34, the use of Fe₉₀Ni₁₀ and Fe whose crystal structures arebody-centered cubic crystals is effective to increase AΔR. In contrast,the use of Ni or Ni₈₀Fe₂₀ has been found to decrease AΔR from the valuebefore the insertion.

Therefore, also when Fe—Ni-system alloys are used as materials of thethin-film insertion layers 32, 34, those having compositions makingbody-centered cubic crystal structures are preferably selected.

SEVENTH EXAMPLE

As the seventh example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (2 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As the material X of the thin-film insertion layers 32, 34, five kindsof Co—Ni-system alloys (Ni, Ni₈₀Co₂₀, Fe₅₀Co₅₀, Co₉₀Ni₁₀ and Co),respectively. Relations between the materials of the thin-film insertionlayers 32, 34 and AΔR obtained thereby are shown below.

X: AΔR (mΩμm²) Not inserted: 0.8 Ni: 0.3 Ni₈₀Co₂₀: 0.5 Ni₅₀Co₅₀: 1.0Co₉₀Ni₁₀: 0.8 Co: 0.6

It has been found from the above result that, in case such Co—Ni-systemalloys are used as materials of the thin-film insertion layers 32, 34,an effect of increasing AΔR is obtained near the composition ofNi₅₀Co₅₀. Also, the use of compositions near Ni or Co has been found todecrease AΔR from the value before the insertion.

EIGHTH EXAMPLE

As the eighth example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (2 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As a material of the thin-film insertion layers 32, 34, (Fe₅₀Co₅₀)₉₇Z₃prepared by mixing 3 atomic % of an element Z (Cu, Ti, Ga, Hf or Mn) inFe₅₀Co₅₀ was used. Relations between elements Z mixed in Fe₅₀Co₅₀ andAΔR obtained thereby are shown below.

Z: AΔR (mΩμm²) Not mixed: 1.55 Cu: 2.9 Ti: 2.7 Ga: 2.4 Hf: 2.7 Mn: 2.2

It as been found from the above result that, when a small quantity ofany of those elements is contained in the Fe₅₀Co₅₀ alloy as thethin-film insertion layer, AΔR increases. As a result of furtherquantitative investigation, it has been found that AΔR increases up toapproximately 30 atomic % of mixture of each of those elements, but thisincrease is remarkable when the mixture is 10 atomic % or less. Thus theeffect of the mixture has been confirmed to be great in the range notsmaller than 5 atomic % and not larger than 10 atomic %.

Also when other elements, namely, Cr, V, Ta, Nb, Zn, Ni and Sc, aremixed respectively, AΔR increased. Furthermore, also when Ge, Y, Tc, Re,Ru, Rh, Ir, Pd, Pt, Ag, Au, B, Al, In, C, Si, Sn, Ca, Sr, Ba, O, N and Fwere mixed respectively, it was effective.

NINTH EXAMPLE

As the ninth example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (2 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As a material of the thin-film insertion layers 32, 34, Fe₉₇Z₃ preparedby mixing 3 atomic % of an element Z (Cr, V, Ta, Nb Cu, Zn or Ga) iniron (Fe) was used. Relations between elements Z mixed and AΔR obtainedthereby are shown below.

Z: AΔR (mΩμm²) Not mixed: 1.35 Cr: 1.45 V: 1.45 Ta: 1.45 Nb: 1.45 Cu:1.80 Zn: 1.75 Ga: 1.70

It as been found from the above result that, when a small quantity ofany of those elements is contained in iron as the thin-film insertionlayer, AΔR increases. As a result of further quantitative investigation,it has been found that AΔR increases up to approximately 30 atomic % ofmixture of each of those elements, but this increase is remarkable whenthe mixture is 10 atomic % or less. Thus the effect of the mixture hasbeen confirmed to be great in the range not smaller than 5 atomic % andnot larger than 10 atomic %.

Also when other elements, namely, Co, Ni, Sc, Ge, Y, Tc, Re, Ru, Rh, Ir,Pd, Pt, Ag, Au, B, Al, In, C, Si, Sn, Ca, Sr, Ba, O, N and F, are mixedrespectively, AΔR increased. Furthermore, also when Fe as the matrixphase was changed to a Fe—Co alloy or Fe—Ni alloy containing Fe by 50atomic % or more, or a Fe—Co—Ni alloy containing Fe by 25 atomic % ormore, equivalent effects were obtained.

TENTH EXAMPLE

As the tenth example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (2 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As a material of the thin-film insertion layers 32, 34, CO₉₇Z₃ preparedby mixing 3 atomic % of an element Z (Sc, Ti, Mn, Cu or Hf) in cobalt(Co) was used. Relations between elements Z mixed and AΔR obtainedthereby are shown below.

Z: AΔR (mΩμm²) Not mixed: 0.6 Sc: 1.0 Ti: 1.2 Mn: 1.0 Cu: 1.5 Hf: 1.0

It has been found from the above result that, when a small quantity ofany of those elements is contained in cobalt as the thin-film insertionlayer, AΔR increases. As a result of further quantitative investigation,it has been found that AΔR increases up to approximately 30 atomic % ofmixture of each of those elements, but this increase is remarkable whenthe mixture is 10 atomic % or less. Thus the effect of the mixture hasbeen confirmed to be great in the range not smaller than 5 atomic % andnot larger than 10 atomic %.

Also when other elements, namely, Fe, Ni, Cr, V, Ta, Nb, Zn, Ga, Ge Zr,Y, Tc, Re, Ru, Rh, Ir, Pd, Pt, Ag, Au, B, Al, In, C, Si, Sn, Ca, Sr, Ba,O, N and F, are mixed respectively, AΔR increased. Furthermore, alsowhen Co as the matrix phase was changed to a Co—Ni alloy containing Coby 50 atomic % or more, or a Fe—Co—Ni alloy containing Co by 25 atomic %or more, equivalent effects were obtained.

ELEVENTH EXAMPLE

As the eleventh example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (2 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As a material of the thin-film insertion layers 32, 34, Ni₉₇Z₃ preparedby mixing 3 atomic % of an element Z (Ti, Mn, Zn, Ga, Ge, Zr or Hf) innickel (Ni) was used. Relations between elements Z mixed and AΔRobtained thereby are shown below.

Z: AΔR (mΩμm²) Not mixed: 0.3 Ti: 0.8 Mn: 0.9 Zn: 1.0 Ga: 0.9 Ge: 0.8Zr: 1.0 Hf: 1.2

It has been found from the above result that, when a small quantity ofany of those elements is contained in nickel as the thin-film insertionlayer, AΔR increases. As a result of further quantitative investigation,it has been found that AΔR increases up to approximately 30 atomic % ofmixture of each of those elements, but this increase is remarkable whenthe mixture is 10 atomic % or less. Thus the effect of the mixture hasbeen confirmed to be great in the range not smaller than 5 atomic % andnot larger than 10 atomic %.

Also when other elements, namely, Fe, Co, Cr, V, Ta, Nb, Sc, Cu, Y, Te,Re, Ru, Rh, Ir, Pd, Pt, Ag, Au, B, Al, In, C, Si, Sn, Ca, Sr, Ba, O, Nor F, are mixed respectively, AΔR increased. Furthermore, also whennickel as the matrix phase was changed to a Ni—Fe or Ni—Co alloycontaining nickel by 50 atomic % or more, or a Fe—Co—Ni alloy containingnickel by 25 atomic % or more, equivalent effects were obtained.

TWELFTH EXAMPLE

As the twelfth example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2-2.3 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (2-2.3 nm) Part ofthe pinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn(15 nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5nm)

As materials X of the thin-film insertion layers 32, 34, the followingfour kinds of materials were used.

(1) Fe₅₀Co₅₀ (2 nm)

(2) (Fe₅₀Co₅₀)₉₇Cu₃ (2 nm)

(3) (Fe₅₀Co₅₀ (1 nm)/Cu (0.1 nm)/Fe₅₀Co₅₀ (1 nm))

(4) (Fe₅₀Co₅₀ (0.7 nm)/Cu (0.1 nm)/Fe₅₀CO₅₀ (0.7 nm)/Cu (0.1nm)/Fe₅₀Co₅₀ (0.7 nm))

In the multi-layered structures shown above, the order of respectivelayers are from near to away from the lower electrode. Relations betweencompositions X of the thin-film insertion layers 32, 34 and AΔR obtainedthereby are shown below.

X: AΔR (mΩμm²) (1): 1.55 (2): 2.9 (3): 3.1 (4): 3.3

It is appreciated from the result shown above that larger AΔR can beobtained when the Cu layer is periodically inserted than when Cu isuniformly mixed in Fe₅₀Co₅₀.

This tendency was not limited to Cu, but also confirmed in structuresmade by periodically inserting a layer that contains at least one kindof element selected from the group consisting of chromium (Cr), vanadium(V), tantalum (Ta), niobium (Nb), scandium (Sc), titanium (Ti),manganese (Mn), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr),hafnium (Hf, yttrium (Y), technetium (Tc), rhenium (Re), ruthenium (Ru),rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver (Ag),gold (Au), boron (B), aluminum (Al), indium (In), carbon (C), silicon(Si), tin (Sn), calcium (Ca), strontium (Sr), barium (Ba), oxygen (O),nitrogen (N) and fluorine (F), and has a thickness not thinner than 0.03nm and not exceeding 1 nm, which permits it to exist as a body-centeredcubic structure in the Fe—Co alloy.

THIRTEENTH EXAMPLE

As the thirteenth example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (4.5nm) Thin-film insertion layer 34: X (0.5 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (0.5 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (4.5 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As materials X of the thin-film insertion layers, Fe_(1-z)Cr_(z) wasused. Relations among Cr quantity Z in the thin-film insertion layer 32or 34, thickness of the thin-film insertion layer and AΔR obtained areshown below. For comparison purposes, data of a structure without thethin-film insertion layer and data of a structure with 2 nm thick pureFe inserted are also shown.

Z: (thickness) AΔR (mΩμm²) 0   (0 nm): 0.8 0   (2 nm): 1.35 0 (0.5 nm):0.9 10 (0.5 nm): 1.3 30 (0.5 nm): 1.5 60 (0.5 nm): 1.4 80 (0.5 nm): 1.2

The above result is explained below. When the 2 nm thick thin-filminsertion layer of pure Fe (Z=0) was inserted, AΔR increased from 0.8(mΩμm²) to 1.35 (mΩμm²). This can be explained as follows.

In case of such a ferromagnetic transition metal, the s-band, p-band andd-band form a mixed band near a portion closer in energy. Majority spinshave a Fermi level in an energy position offset from the mixed band, anddo not scatter easily. However, minority spins have a Fermi level in theregion of the mixed band, and are liable to scatter. This is the originof the magnetoresistance effect. Therefore, for estimating whether themagnetoresistance change is large or small, it is an index how near tothe center of the mixed band those minority spins have the Fermi level,or how far from the mixed band those majority spins have the Fermilevel.

Transition metals can typically form face-centered cubic crystals andbody-centered cubic crystals as their crystal structures. In case of ametal system including Fe, Co and Ni, for example, the Fermi level ofminority spins is generally more centered in the mixed band when themetal forms a body-centered cubic crystal than a face-centered cubiccrystal. Therefore, body-centered cubic crystals are more desirable forincreasing the magnetoresistance effect. This may be one of reasons whyAΔR rises when pure Fe is inserted as the thin-film insertion layer inthis Example.

If the thickness of pure Fe is thinned from 2 nm to 0.5 nm, then AΔRdecreases to 0.9 (mΩμm²). This is probably because very thin Fe isdifficult to form a body-centered cubic crystal as its crystalstructure. In contrast, when Cr was contained in the thin-film insertionlayer so as to reliably form a body-centered cubic crystal over theentire composition range, AΔR increased more than the use of pure Fe(0.5 nm).

Curie temperatures of Fe—Cr alloys decrease as Cr is increased, andthese alloys exhibit paramagnetism at room temperatures when Cr isincreased to 70 atomic % or more. However, if Fe—Cr itself is very thinand a ferromagnetic material is adjacently located, ferromagnetism isinduced, and a magnetoresistance effect is obtained.

FOURTEENTH EXAMPLE

As the fourteenth example, magnetoresistance effect elements having thefollowing film configuration were prepared.

Protective layer 22: Ta (10 nm) Part of the free layer 20: Co₉₀Fe₁₀ (4.5nm) Thin-film insertion layer 34: X (0.5 nm) Nonmagnetic intermediatelayer 18: Cu (3 nm) Thin-film insertion layer 32: X (0.5 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (4.5 nm) Anti-ferromagnetic layer 14: PtMn (15nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As materials X of the thin-film insertion layers, Fe_(1-z)V_(z) wasused. Relations among V quantity Z in the thin-film insertion layer 32or 34, thickness of the thin-film insertion layer and AΔR obtained areshown below. For comparison purposes, data of a structure without thethin-film insertion layer and data of a structure with 2 nm thick pureFe inserted are also shown.

Z: (thickness) AΔR (mΩμm²) 0   (0 nm): 0.8 0   (2 nm): 1.35 0 (0.5 nm):0.9 10 (0.5 nm): 1.2 30 (0.5 nm): 1.3 60 (0.5 nm): 1.1 80 (0.5 nm): 1.1

As already explained in conjunction with the eighth example, the effectof increasing AΔR by insertion of Fe forming a body-centered cubiccrystal slightly degrades when the thin-film insertion film is verythin. Taking it into account, the content of V was adjusted to stabilizethe body-centered cubic crystal. Then AΔR recovered.

Fe—V alloys also exhibit paramagnetism when V occupies 70 atomic % ormore. However, if Fe—V itself is very thin and a ferromagnetic materialis adjacently located, ferromagnetism is induced, and amagnetoresistance effect is obtained.

Increase of AΔR by stabilization of the body-centered cubic crystalmentioned above was confirmed also when using Fe—Co alloys (Co: notexceeding 80 atomic %), Fe—Ni alloys (Ni: not exceeding 10 atomic %),Fe—Rh alloys (Rh: 11 to 55 atomic %), Fe—Ti alloys (Ti: 49 to 51 atomic%), Fe—Co—Ni alloys in the composition region of body-centered cubiccrystals, and Co—Mn—Fe alloys in the composition region of body-centeredcubic crystals.

Furthermore, an effect of increasing AΔR was confirmed also when usingthese alloys as the matrix phase and mixing 0.5 to 30 atomic % of atleast one kind of element selected from the group consisting of Sc, Ti,Mn, Cu, Zn, Ga, Ge, Zr, Hf, Y,}Tc, Re, Ru, Rh, Ir, Pd, Pt, Ag, Au, B,Al, In, C, Si, Sn, Ca, Sr and Ba and not included in the matrix alloys.

FIFTEENTH EXAMPLE

As the fifteenth example of the invention, a version using Au (gold) asthe nonmagnetic intermediate layer 18. In this example,magnetoresistance effect elements having the following filmconfiguration were prepared.

Protective layer 22: Ta (10 nm)  Part of the free layer 20: Co₉₀Fe₁₀ (3nm) Thin-film insertion layer 34: X (2 nm) Nonmagnetic intermediatelayer 18: Au (3 nm) Thin-film insertion layer 32: X (2 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (3 nm) Anti-ferromagnetic layer 14: PtMn (15nm)  Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

As materials X of the thin-film insertion layers, five kinds of Fe—Coalloys (Co, Co₉₀Fe₁₀, Fe₅₀Co₅₀, Fe₈₀Co₂₀ and Fe) were used. Values ofAΔR obtained are shown below. For comparison purposes, data of astructure without the thin-film insertion layer and data of a structurewith 2 nm thick pure Fe inserted are also shown.

X: AΔR (mΩμm²) Co: 0.3 Co₉₀Fe₁₀: 0.4 Fe₅₀Co₅₀: 0.9 Fe₈₀Co₂₀: 1.45 Fe:1.7

As shown above, as Fe concentration in the thin-film insertion layers32, 34 using Au as the nonmagnetic intermediate layer 18 increases, AΔRtended to increase. As such, to increase AΔR, it is important toappropriately select materials of the thin-film insertion layer 32, 34in accordance with the material of the nonmagnetic intermediate layer18.

SIXTEENTH EXAMPLE

As the sixteenth example of the invention, a structure having a backinsertion layer 36 as shown in FIG. 14 was reviewed. Its result isexplained below. First, magnetoresistance effect elements having thethin-film insertion layers as shown below were prepared, and theirresults were investigated.

Sample A: Standard Structure (FIG. 1)

Protective layer 22: Ta (10 nm)  Part of the free layer 20: Co₉₀Fe₁₀ (4nm) Thin-film insertion layer 34: Fe₅₀Co₅₀ (1 nm) Nonmagneticintermediate layer 18: Cu (3 nm) Thin-film insertion layer 32: Fe₅₀Co₅₀(1 nm) Part of the pinned layer 16: Co₉₀Fe₁₀ (4 nm) Anti-ferromagneticlayer 14: PtMn (15 nm)  Second base layer 12: NiFeCr (5 nm) First baselayer 12: Ta (5 nm)

Sample B: Structure having the Back Insertion Layer (FIG. 14)

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm) Partof the free layer 20: Co₉₀Fe₁₀ (4 nm) Thin-film insertion layer 34:Fe₅₀Co₅₀ (1 nm) Nonmagnetic intermediate layer 18: Cu (3 nm) Thin-filminsertion layer 32: Fe₅₀Co₅₀ (1 nm) Part of the pinned layer 16:Co₉₀Fe₁₀ (4 nm) Anti-ferromagnetic layer 14: PtMn (15 nm)  Second baselayer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

AΔR of Sample A was 1.2 (mΩμm²), but AΔR of Sample B having the backinsertion layer 36 increased up to 1.5 (mΩμm²). This is probably becausespin-dependent interface scattering occurred along the interface betweenthe free layer 20 and the back insertion layer 36.

This effect can be obtained also when the anti-ferromagnetic layer 14 islocated in an upper position.

SEVENTEENTH EXAMPLE

As the seventeenth example of the invention, a review was made abouteffects obtained by inserting thin-film insertion layers in structureshaving the back insertion layer 36. Its result is explained below.First, seven different Samples C through I were prepared asmagnetoresistance effect elements having the back insertion layer asshown below, and effects obtained-thereby were reviewed.

Sample C: Not Including Thin-Film Insertion Layers (FIG. 14)

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm) Partof the free layer 20: Co₉₀Fe₁₀ (5 nm) Nonmagnetic intermediate layer 18:Cu (3 nm) Pinned layer 16: Co₉₀Fe₁₀ (4 nm) Anti-ferromagnetic layer 14:PtMn (15 nm)  Second base layer 12: NiFeCr (5 nm) First base layer 12:Ta (5 nm)

Sample D: Inserting the Thin-Film Inserting Layer 32 Between the PinnedLayer 16 and the Anti-Ferromagnetic Layer 14 (FIG. 16)

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm) Partof the free layer 20: Co₉₀Fe₁₀ (5 nm) Nonmagnetic intermediate layer 18:Cu (3 nm) Part of the pinned layer 16: Co₉₀Fe₁₀ (4 nm) Thin-filminsertion layer 32: Fe₅₀Co₅₀ (1 nm) Anti-ferromagnetic layer 14: PtMn(15 nm)  Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5nm)

Sample E: Inserting the Thin-Film Insertion Layer 32 in the Pinned Layer16 (FIG. 17)

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm) Partof the free layer 20: Co₉₀Fe₁₀ (5 nm) Nonmagnetic intermediate layer 18:Cu (3 nm) Part of the pinned layer 16: Co₉₀Fe₁₀ (2 nm) Thin-filminsertion layer 32: Fe₅₀Co₅₀ (1 nm) Part of the pinned layer 16:Co₉₀Fe₁₀ (2 nm) Anti-ferromagnetic layer 14: PtMn (15 nm)  Second baselayer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

Sample F: Inserting the Thin-Film Insertion Layer 32 Between the PinnedLayer 16 and the Nonmagnetic Intermediate Layer 18 (FIG. 18)

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm) Partof the free layer 20: Co₉₀Fe₁₀ (5 nm) Nonmagnetic intermediate layer 18:Cu (3 nm) Thin-film insertion layer 32: Fe₅₀Co₅₀ (1 nm) Part of thepinned layer 16: Co₉₀Fe₁₀ (4 nm) Anti-ferromagnetic layer 14: PtMn (15nm)  Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

Sample G: Inserting the Thin-Film Insertion Layer 34 Between theNonmagnetic Intermediate Layer 18 and the Free Layer 20 (FIG. 19)

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm) Partof the free layer 20: Co₉₀Fe₁₀ (4 nm) Thin-film insertion layer 32:Fe₅₀Co₅₀ (1 nm) Nonmagnetic intermediate layer 18: Cu (3 nm) Pinnedlayer 16: Co₉₀Fe₁₀ (5 nm) Anti-ferromagnetic layer 14: PtMn (15 nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

Sample H: Inserting the Thin-Film Insertion Layer 34 in the Free Layer20 (FIG. 20)

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm) Partof the free layer 20: Co₉₀Fe₁₀ (2 nm) Thin-film insertion layer 34:Fe₅₀Co₅₀ (1 nm) Part of the free layer 20: Co₉₀Fe₁₀ (2 nm) Nonmagneticintermediate layer 18: Cu (3 nm) Pinned layer 16: Co₉₀Fe₁₀ (5 nm)Anti-ferromagnetic layer 14: PtMn (15 nm)  Second base layer 12: NiFeCr(5 nm) First base layer 12: Ta (5 nm)

Sample I: Inserting the Thin-Film Insertion Layer 34 Between the FreeLayer 20 and the Back Insertion Layer 36 (FIG. 21)

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm)Thin-film insertion layer 34: Fe₅₀Co₅₀ (1 nm) Part of the free layer 20:Co₉₀Fe₁₀ (4 nm) Nonmagnetic intermediate layer 18: Cu (3 nm) Pinnedlayer 16: Co₉₀Fe₁₀ (5 nm) Anti-ferromagnetic layer 14: PtMn (15 nm) Second base layer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

With Samples C through I, AΔR was evaluated. Its result is as follows.

Sample AΔR (mΩμm²) C: 0.9 D: 1.0 E: 1.0 F: 1.2 G: 1.2 H: 1.0 I: 1.1

The effect of increasing AΔR was largest when the thin-film insertionlayer 32 or 34 was located along the interface between the pinned layer16 and the nonmagnetic intermediate layer (Sample F) or along theinterface between the free layer 20 and the nonmagnetic intermediatelayer 18 (Sample G). The effect was next largest when the layer 32 or 34was inserted as the interface between the free layer 20 and the backinsertion layer 36. This is probably caused by an increase ofspin-dependent interface scattering.

Even in Samples D, E and H, AΔR increases to a certain extent. One ofreasons there of is that spin-dependent bulk scattering is larger inCo₉₀Fe₁₀ than in Co₅₀Fe₅₀. Additionally, the increase can rely on thatthe band structure of the pinned layer or free layer is modulated by themulti-layered crystal structure including the layer of a face-centeredcubic crystal and a layer of the body-centered cubic crystal, andthereby increases the difference in conductivity between majority spinsand minority spins.

EIGHTEENTH EXAMPLE

In the preceding seventeenth example, effects by the location of onethin-film insertion layer were discussed. The instant example combinesSamples F, G and I that were remarkably effective to enhance theincrease of AΔR. More specifically, Samples J and K were prepared asmagnetoresistance effect elements having the back insertion layer, andtheir properties were reviewed.

Sample J: locating the Fe₅₀Co₅₀ thin-film insertion layer as theinterface between the pinned layer 16 and the nonmagnetic intermediatelayer 18, and as the interface between the free layer 20 and thenonmagnetic intermediate layer 18

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm) Partof the free layer 20: Co₉₀Fe₁₀ (4 nm) Thin-film insertion layer 34:Fe₅₀Co₅₀ (1 nm) Nonmagnetic intermediate layer 18: Cu (3 nm) Thin-filminsertion layer 34: Fe₅₀Co₅₀ (1 nm) Part of the pinned layer 16:Co₉₀Fe₁₀ (4 nm) Anti-ferromagnetic layer 14: PtMn (15 nm)  Second baselayer 12: NiFeCr (5 nm) First base layer 12: Ta (5 nm)

Sample K: locating the Fe₅₀Co₅₀ thin-film insertion layer as theinterface between the pinned layer 16 and the nonmagnetic intermediatelayer 18, and as the interface between the free layer 20 and the backinsertion layer 36

Protective layer 22: Ta (10 nm)  Back insertion layer 36: Cu (1 nm)Thin-film insertion layer 32: Fe₅₀Co₅₀ (1 nm) Part of the free layer 20:Co₉₀Fe₁₀ (4 nm) Thin-film insertion layer 32: Fe₅₀Co₅₀ (1 nm)Nonmagnetic intermediate layer 18: Cu (3 nm) Thin-film insertion layer32: Fe₅₀Co₅₀ (1 nm) Part of the pinned layer 16: Co₉₀Fe₁₀ (4 nm)Anti-ferromagnetic layer 14: PtMn (15 nm)  Second base layer 12: NiFeCr(5 nm) First base layer 12: Ta (5 nm)

As a result, AΔR was as high as 1.3 (mΩμm²) in Sample J, and as high as1.7 (mΩμm²) in Sample K as expected, and as compared with Sample F andSample G (AΔR=1.2 (mΩμm²)) and Sample I (AΔR=1.1 (mΩμm²)) inserting onlyone thin-film insertion layer, increase of AΔR was confirmed.

NINETEENTH EXAMPLE

In this example, a top-type spin valve structure locating theanti-ferromagnetic layer 14 in an upper position as shown in FIG. 2 wasprepared, and its properties were evaluated. As a result, similarly tothe foregoing examples, an effect of increasing the magnetoresistancechange by the thin-film insertions layers 32, 34 and back insertionlayer 36 was confirmed.

TWENTIETH EXAMPLE

In this example, an effect of inserting the thin-film insertion layers32, 34 and back insertion layer 36 in magnetoresistance effect elementsof a “multi-layered ferri-structure” was estimated.

FIG. 3 is a diagram that schematically shows a cross-sectional structureof a magnetoresistance effect element having a multi-layeredferri-structure. That is, the first pinned layer 16A and the secondpinned layer 16B are stacked via the anti-parallel coupling layer 40.Also in the magnetoresistance effect element having the pinned layer ofthe multi-layered ferri-structure, an effect of increasing themagnetoresistance change by the use of the thin-film insertion layers32, 34 and back insertion layer 36 was confirmed similarly to theforegoing examples.

FIG. 22 is a diagram that schematically shows another specific exampleof the cross-sectional structure of a magnetoresistance effect elementhaving a multi-layered ferri-structure.

More specifically, the magnetoresistance effect element shown here has astructure depositing the lower electrode 54, base layer 12,anti-ferromagnetic layer 14, pinned layer 16 in form of a three-layeredstructure of the first pined layer 16A, anti-parallel coupling layer 40and second pinned layer 16B, nonmagnetic intermediate layer 18, freelayer 20 in form of a three-layered structure of the first pinned layer20A, anti-parallel coupling layer 40 and second free layer 20B,protective layer 22 and upper electrode 52 sequentially in this order.

Also in the magnetoresistance effect element having the pinned layer 16and the free layer 20 each in form of a multi-layered ferri-structure,an effect of increasing the magnetoresistance change by the use of thethin-film insertion layers 32, 34 and back insertion layer 36 wasconfirmed similarly to the foregoing examples.

TWENTY-FIRST EXAMPLE

FIG. 23 is a diagram that schematically shows a cross-sectionalstructure of a magnetoresistance effect element having a resistanceadjusting layer. A resistance adjusting layer 38 having ahigh-resistance made by oxidizing a Cu₁₀Cr₉₀ alloy is inserted in thenonmagnetic intermediate layer 18. The resistance adjusting layer 38locally includes low-resistance, conductive regions as pinholes, and thesense current by perpendicular current supply will concentrically flowsinto the pinholes. As a result, its effective current-supply region isnarrowed, and it results in increasing the output. If only acurrent-supply region exhibiting large spin-dependent scattering can benarrowed, the increase of the resistance change (AΔR) will increaserelative to the increase of the entire resistance value (AR), and theratio of resistance change (MR=AΔR/AR) will increase accordingly.Therefore, larger effect is expected by combining a spin valve elementaccording to the embodiment of the invention having a thin-filminsertion layer with large spin-dependent scattering along theinterface. Using a SyAF structure, samples with and without theresistance adjusting layer 38 and with and without the interfaceinsertion layers 32 and 34 were compared.

-   Sample A: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/Fe₈₀Co₂₀ 1 nm/Cu 2 nm/Fe₅₀Co₅₀ 0.5 nm/Ni₈₀Fe₂₀ 3    nm/Co₉₀Fe₁₀ 1 nm/Ta 10 nm-   Sample B: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/Fe₈₀Co₂₀ 1 nm/Cu 0.2 nm/(Cu₁₀Cr₉₀)—O 0.8 nm/Cu    0.2 nm/Ni₈₀Fe₂₀ 3.5 nm/Co₉₀Fe₁₀ 1 nm/Cu 1 nm/Ta 10 nm-   Sample C: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/Fe₈₀Co₂₀ 1 nm/Cu 0.2 nm/(Cu₁₀Cr₉₀)—O 0.8 nm/Cu    0.2 nm/Fe₅₀Co₅₀ 0.5 nm/Ni₈₀Fe₂₀ 3 nm/Co₉₀Fe₁₀ 1 nm/Cu 1 nm/Ta 10 nm-   Sample D: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/Fe₈₀Co₂₀ 1 nm/Cu 0.2 nm/(Cu₁₀Al₉₀)—O 0.8 nm/Cu    0.2 nm/Fe₅₀Co₅₀ 0.5 nm/Ni₈₀Fe₂₀ 3 nm/Co₉₀Fe₁₀ 1 nm/Cu 1 nm/Ta 10 nm

Oxidization intensity of Samples C and D is 30 k Langmuires. In Sample Ahaving no resistance adjusting layer, output AΔR was 1.5 mΩμm², but inSample C having the resistance adjusting layer 38, AΔR was 15 mΩμm².Even in structures similarly having such resistance adjusting layers 38,AΔR was 15 mΩμm² in Sample C having the thin-film insertion layers 32and 34, but AΔR was 10 mΩμm² in Sample B removing the thin-filminsertion layers 32 and 34 to equalize the total film thickness. It hasbeen confirmed from these facts that the thin-film insertion layers 32and 34 and the resistance adjusting layer 38, when combined, collaborateto enhance the effect.

In Sample D using an oxide of Cu₁₀Al₉₀ alloy as the resistance adjustinglayer 38, AΔR was as large as 16 mΩμm², and an effect of currentconfinement and the interface insertion layers 32 and 34 was confirmed.Additionally, some samples having the same film configuration as SampleC were prepared by changing the oxidation process as follows.

-   Sample E: oxidization by radical oxygen (oxidization intensity: 800    Langmuires)-   Sample F: plasma oxidation (oxidization intensity: 800 Langmuires)-   Sample G: oxidization under irradiation of Ar ion beams (oxidization    intensity: 800 Langmuires)-   Sample H: oxidization after irradiation of Ar ion beams (oxidization    intensity: 3 k Langmuires)

As a result, in the order of Samples E, F and G, AΔR was 20 mΩμm², 50mΩμm² and 50 mΩμm² probably because the current path in the resistanceadjusting layer 38 became more conductive and the insulating portion wasconversely enhanced in insulating performance. Furthermore, Samples C,E, F and G were additionally annealed. As a result, the output AΔRincreased up to 20 mΩμm², 40 mΩμm², 80 mΩμm² and 80 mΩμm², respectively.

Similar improvement of AΔR has been observed in the magnetoresistanceeffect elements where the resistance adjusting layer 38 includes anoxide of at least one kind of element selected from the group consistingof boron (B), silicon (Si), germanium (Ge), tantalum (Ta), tungsten (W),niobium (Nb), aluminum (Al), molybdenum (Mo), phosphorus (P), vanadium(V), arsenic (As), antimony (Sb), zirconium (Zr), titanium (Ti), zinc(Zn), lead (Pb), thorium (Th), beryllium (Be), cadmium (Cd), scandium(Sc), lanthanum (La), yttrium (Y), praseodymium (Pr), chromium (Cr), tin(Sn), gallium (Ga), indium (In), rhodium (Rh), magnesium (Mg), lithium(Li), barium (Ba), calcium (Ca), strontium (Sr), manganese (Mn), iron(Fe), cobalt (Co), nickel (Ni), rubidium (Rb) and rare earth metals, asmajor component thereof, and the oxide includes an element selected fromthe group consisting of copper (Cu), gold (Au), silver (Ag), platinum(Pt), palladium (Pd), iridium (Ir) and osmium (Os) not less than 1atomic % and not exceeding 50 atomic %.

TWENTY-SECOND EXAMPLE

FIG. 24 is a diagram that schematically shows a cross-sectionalstructure of a magnetoresistance effect element having a resistanceadjusting layer. A resistance adjusting layer 38 having ahigh-resistance made by oxidizing a Cu₁₀Cr₉₀ alloy is inserted in themagnetically pinned layer 16B and the magnetically free layer 20,respectively. The resistance adjusting layers 38 locally includeslow-resistance, conductive regions as pin holes, and the sense currentby perpendicular current supply will concentrically flows into thepinholes. As a result, its effective current-supply region is narrowed,and it results in increasing the output. If only a current-supply regionexhibiting large spin-dependent scattering can be narrowed, the increaseof the resistance change (AΔR) will increase relative to the increase ofMe entire resistance value (AR), and the ratio of resistance change(MR=AΔR/AR) will increase accordingly. Therefore, larger effect isexpected by combining a spin valve element according to the embodimentof the invention having thin-film insertion layers 32 and 34 with largespin-dependent scattering along the interface. Using a SyAF structure,samples with and without the resistance adjusting layers 38 and with andwithout the interface insertion layers 32 and 34 were compared.

-   Sample A: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/Fe₈₀Co₂₀ 1 nm/Cu 2 nm/Fe₅₀Co₅₀ 0.5 nm/Ni₈₀Fe₂₀ 3    nm/Co₉₀Fe₁₀ 1 nm/Ta 10 nm-   Sample B: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/(Cu₁₀Cr₉₀)—O 0.8 nm/Fe₈₀Co₂₀ 1 nm/Cu 2    nm/Fe₅₀Co₅₀ 0.5 nm/Ni₅₀Fe₂₀ 3 nm/Co₉₀Fe₁₀ 1 nm/Cu 1 nm/Ta 10 nm-   Sample C: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/Fe₈₀Co₂₀ 0.5 nm/(Cu₁₀Cr₉₀)—O 0.8 nm/Fe₈₀Co₂₀ 0.5    nm/Cu 2 nm/Fe₅₀Co₅₀ 0.5 nm/Ni₅₀Fe₂₀ 3 nm/Co₉₀Fe₁₀ 1 nm/Cu 1 nm/Ta 10    nm-   Sample D: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/Fe₈₀Co₂₀ 0.5 nm/(Cu₁₀Cr₉₀)—O 0.8 nm/Fe₈₀Co₂₀ 0.5    nm/Cu 2 nm/Fe₅₀Co₅₀ 0.5 nm//(Cu₉₀Cr₁₀)—O 0.8 nm/Ni₈₀Fe₂₀ 3    nm/Co₉₀Fe₁₀ 1 nm/Cu 1 nm/Ta 10 nm-   Sample E: Ta 5 nm/NiFeCr 5 nm/PtMn 15 nm/(Co₉₀Fe₁₀)₉₀Cr₁₀ 3 nm/Ru 1    nm/Fe₅₀Co₅₀ 2.5 nm/Fe₈₀Co₂₀ 0.5 nm/(Cu₁₀Al₉₀)—O 0.8 nm/Fe₈₀Co₂O 0.5    nm/Cu 2 nm/Fe₅₀Co₅₀ 0.5 nm//(Cu₉₀Cr₁₀)—O 0.8 nm/Ni₈₀Fe₂₀ 3    nm/Co₉₀Fe₁₀ 1 nm/Cu 1 nm/Ta 10 nm

In Sample A having no resistance adjusting layer, output AΔR was 1.5mΩμm², but in Sample B having the resistance adjusting layer 38 in thepinned layer 16B, AΔR was 8 mΩμm². In Sample C, AΔR was 12 mΩμm². InSample D inserting the resistance adjusting layer 38 also in the freelayer 20, AΔR increased to 20 mΩμm². As such, the output can beincreased by inserting the resistance adjusting layer 38 in one or moremagnetic layers, particularly near the non-magnetic intermediate layer18. Also in Sample E using an oxidized Cu₁₀Cl₉₀ as theresistance-adjusting layer, AΔR reached 25 mΩμm².

Similar improvement of AΔR has been observed in the magnetoresistanceeffect elements where the resistance adjusting layer 38 includes anoxide of at least one kind of element selected from the group consistingof boron (B), silicon (Si), germanium (Ge), tantalum (Ta), tungsten (W),niobium (Nb), aluminum (Al), molybdenum (Mo), phosphorus (P), vanadium(V), arsenic (As), antimony (Sb), zirconium (Zr), titanium (Ti), zinc(Zn), lead (Pb), thorium (Th), beryllium (Be), cadmium (Cd), scandium(Sc), lanthanum (La), yttrium (Y), praseodymium (Pr), chromium (Cr), tin(Sn), gallium (Ga), indium (In), rhodium (Rh), magnesium (Mg), lithium(Li), barium (Ba), calcium (Ca), strontium (Sr), manganese (Mn), iron(Fe), cobalt (Co), nickel (Ni), rubidium (Rb) and rare earth metals, asmajor component thereof, and the oxide includes an element selected fromthe group consisting of copper (Cu), gold (Au), silver (Ag), platinum(Pt), palladium (Pd), iridium (Ir) and osmium (Os) not less than 1atomic % and not exceeding 50 atomic %.

TWENTY-THIRD EXAMPLE

In this example, effects of thin-film insertion layers and backinsertion layer in so-called “dual type” magnetoresistance effectelements were confirmed.

FIG. 25 is a diagram that schematically shows a cross-sectionalstructure of a dual type magnetoresistance effect element. Themagnetoresistance effect element shown here has a structure sequentiallydepositing, in the written order, the lower electrode 54, base layer 12,first anti-ferromagnetic layer 14A, first pinned layer 16A, firstnonmagnetic intermediate layer 18A, free layer 20, second nonmagneticintermediate layer 18B, second pinned layer 16B, secondanti-ferromagnetic layer 14B, protective layer 22 and upper electrode52.

Also in the magnetoresistance effect elements having this dualstructure, the effect of increasing the magnetoresistance change by thethin-film insertion layers 32, 34 and back insertion layer 36 wasconfirmed similarly to the foregoing examples, and they exhibitedmagnetoresistance change as large as 1.5 to 3 times that of a standardmagnetoresistance effect element having a pair of pinned layer and freelayer.

TWENTY-FOURTH EXAMPLE

In this example, magnetoresistance effect elements having the pinnedlayer and the free layer each in form of a multi-layered structurealternately depositing a ferromagnetic layer and a nonmagnetic layerwere prepared, and effects by insertion of the thin-film insertion layerand back insertion layer were confirmed.

FIG. 4 is a diagram that schematically illustrates a cross-sectionalstructure of the magnetoresistance effect element according to theinstant example. This magnetoresistance effect element has amulti-layered structure sequentially depositing, in the written order,the lower electrode 54, base layer 12, anti-ferromagnetic layer 14,pinned layer 16 in form of a multi-layered structure alternatelydepositing a ferromagnetic layer F and a nonmagnetic layer N,nonmagnetic intermediate layer 18, free layer 20 in form of amulti-layered structure alternately depositing a ferromagnetic layer Fand a nonmagnetic layer N, protective layer 22 and upper electrode 52.

In each of the pinned layer 16 and the free layer 20 of this element,ferromagnetic layers F get into ferromagnetic coupling with each othervia the nonmagnetic layer N.

Also in the magnetoresistance effect elements having this multi-layeredstructure, the effect of increasing the magnetoresistance change by thethin-fi insertion layers 32, 34 and back insertion layer 36 wasconfirmed similarly to the foregoing examples. That is, in this example,the change of magnetoresistance was increased by using a thin-filminsertion layer having the composition and the crystal structureexplained in any one of the foregoing examples to form one or more ofthe ferromagnetic layers F forming the pinned layer 16 and the freelayer 20, respectively.

TWENTY-FIFTH EXAMPLE

In this example, magnetoresistance effect elements having the pinnedlayer and the free layer each in form of a multi-layered structurealternately depositing two different kinds of ferromagnetic layers F1,F2 were prepared, and effects by insertion of the thin-film insertionlayer and back insertion layer were confirmed.

FIG. 5 is a diagram that schematically illustrates a cross-sectionalstructure of the magnetoresistance effect element according to thisexample. This magnetoresistance effect element has a multi-layeredstructure sequentially depositing, in the written order, the lowerelectrode 54, base layer 12, anti-ferromagnetic layer 14, pinned layer16 in form of a multi-layered structure alternately depositing the firstferromagnetic layer F1 and the second ferromagnetic layer F2,nonmagnetic intermediate layer 18, free layer 20 in form of amulti-layered structure alternately depositing the first ferromagneticlayer F1 and the second ferromagnetic layer F2, protective layer 22 andupper electrode 52.

Also in the magnetoresistance effect elements having this multi-layeredstructure, the effect of increasing the magnetoresistance change by thethin-film insertion layers 32, 34 and back insertion layer 36 wasconfirmed similarly to the foregoing examples. That is, in this example,the change of magnetoresistance was increased by using a thin-filminsertion layer having the composition and the crystal structureexplained in any one of the foregoing examples to form one of the firstand second ferromagnetic layers F1, F2 forming the pinned layer 16 andthe free layer 20, respectively.

TWENTY-SIXTH EXAMPLE

Next explained is the twenty-sixth example of the invention, which is amagnetic reproducing apparatus having inboard any of themagnetoresistance effect element explained with reference to FIGS. 1through 25.

FIG. 26 is a perspective view that shows outline configuration of thiskind of magnetic reproducing apparatus. The magnetic reproducingapparatus 150 shown here is of a type using a rotary actuator. Amagnetic reproducing medium disk 200 is mounted on a spindle 152 androtated in the arrow A direction by a motor, not shown, which isresponsive to a control signal from a controller of a driving mechanism,not shown. The magnetic reproducing apparatus 150 shown here may have aplurality of medium disks 200 inboard.

The medium disk 200 may be of a “lateral recording type” in whichdirections of the recording bits are substantially in parallel to thedisk surface or may be of a “perpendicular recording type” in whichdirections of the recording bits are substantially perpendicular to thedisk surface.

A head slider 153 for carrying out recording and reproduction ofinformation to be stored in the medium disk 200 is attached to the tipof a film-shaped suspension 154. The head slider 153 supports amagnetoresistance effect element or magnetic head, for example,according to one of the foregoing embodiments of the invention, near thedistal end thereof.

Once the medium disk 200 rotates, the medium-facing surface (ABS) of thehead slider 153 is held floating by a predetermined distance above thesurface of the medium disk 200. Also acceptable is a so-called“contact-traveling type” in which the slider contacts the medium disk200.

The suspension 154 is connected to one end of an actuator arm 155 havinga bobbin portion for holding a drive coil, not shown, and others. At theopposite end of the actuator arm 155, a voice coil motor 156, a kind oflinear motor, is provided. The voice coil motor 156 comprises a drivecoil, not shown, wound on the bobbin portion of the actuator arm 155,and a magnetic circuit made up of a permanent magnet and an opposed yokethat are opposed to sandwich the drive coil.

The actuator arm 155 is supported by ball bearings, not shown, which arelocated at upper and lower two positions of the spindle 157 and drivenby the voice coil motor 156 for rotating, sliding movements.

FIG. 27 is a perspective view of a magnetic head assembly at the distalend from an actuator arm 155 involved, which is viewed from the disk.The magnetic head assembly 160 includes the actuator arm 155 having thebobbin portion supporting the drive coil, for example, and thesuspension 154 is connected to one end of the actuator arm 155.

At the distal end of the suspension 154, a head slider 153 carrying themagnetoresistance effect element as explained with reference to FIGS. 1through 25 is provided. The suspension 154 has a lead 164 for writingand reading signals, and the lead line 164 is connected to electrodes ofthe magnetic head incorporated in the head slider 153. Numeral 165 inFIG. 27 denotes an electrode pad of the magnetic head assembly 160.

In this embodiment, one of the magnetoresistance effect elements alreadyexplained in conjunction with the aforementioned embodiments is used asthe magnetoresistance effect element, information magnetically recordedon the medium disk 200 under a higher recording density than before canbe read reliably.

Heretofore, some embodiments of the invention have been explained withreference to specific examples. However, the invention is not limited tothese specific examples.

For example, as to laminating configuration of the components composingthe magnetoresistive effect element, such as the specific size, shape orpositional relationship of the electrode, bias magnetic field applyingfilm or insulating layer can be selected from the known art. Theinvention encompasses any such changes by persons skilled in the artprovided they attain the effects of respective embodiments of theinvention.

The each components of the magnetoresistance effect element such as theantiferromagnetic layer, magnetically pinned layer, nonmagnetic spacerlayer or magnetically free layer can be made of a single layer or madeof multiplayer including a plurality of films.

When the magnetoresistance effect element according to the presentinvention is applied to a reproducing head, a recording-reproducingintegrated magnetic head may be realized by combining a recording headtherewith.

Further, the magnetic reproducing apparatus according to the presentinvention may be of a fixed type in which specific magnetic recordingmedium is permanently installed, while it may be of a removable type inwhich the magnetic recording medium can be replaced easily.

Further, the magnetoresistance effect element according to the presentinvention can be advantageously used for a magnetic memory such asmagnetic random-access memory (MRAM).

As described above, embodiments of the invention can increase theresistance change by inserting a thin-film insertion layer or backinsertion layer having a unique composition or crystal structure in themagnetoresistance effect film of a CPP type magnetoresistance effectelement having a pin valve structure, and can realize highly sensitiveread that cannot be realized with a conventional CPP typemagnetoresistance effect element having a spin valve structure.

While the present invention has been disclosed in terms of theembodiment in order to facilitate better understanding thereof, itshould be appreciated that the invention can be embodied in various wayswithout departing from the principle of the invention. Therefore, theinvention should be understood to include all possible embodiments andmodification to the shown embodiments which can be embodied withoutdeparting from the principle of the invention as set forth in theappended claims.

1. A magnetoresistance effect element, comprising: a magnetoresistanceeffect film including a magnetically pinned layer having a magneticmaterial film whose direction of magnetization is pinned substantiallyin one direction, a magnetically free layer having a magnetic materialfilm whose direction of magnetization changes in response to an externalmagnetic field, and nonmagnetic metal intermediate multilayers locatedbetween said magnetically pinned layer and said magnetically free layer;and a pair of electrodes electrically connected to saidmagnetoresistance effect film to supply a sense current perpendicularlyto a film plane of said magnetoresistance effect film, at least one ofsaid magnetically pinned layer and said magnetically free layerincluding a thin-film insertion layer, said nonmagnetic metalintermediate multilayers having a resistance adjusting layer that iscomposed of Cu—Cr oxide or Cu—Al oxide, and said thin-film insertionlayer composed of iron (Fe) and cobalt (Co).
 2. The magnetoresistanceeffect element according to claim 1, wherein said resistance adjustinglayer has a thickness not thinner than 0.2 nm and not exceeding 3 nm. 3.The magnetoresistance effect element according to claim 1, wherein saidresistance adjusting layer is placed at a distance of 0 to 1 nm from aninterface in contact with said magnetically free layer.
 4. Themagnetoresistance effect element according to claim 1, wherein saidresistance adjusting layer is placed at a distance of 0 to 1 nm from aninterface in contact with said magnetically pinned layer.
 5. Themagnetoresistance effect element according to claim 1, wherein saidresistance adjusting layer includes oxide parts and metallic parts, saidoxide parts including at least one kind of element selected from thegroup consisting of boron (B), silicon (Si), germanium (Ge), tantalum(Ta), tungsten (W), niobium (Nb), aluminum (Al), molybdenum (Mo),phosphorus (P), vanadium (V), arsenic (As), antimony (Sb), zirconium(Zr), titanium (Ti), zinc (Zn), lead (Pb), thorium (Th), beryllium (Be),cadmium (Cd), scandium (Sc), lanthanum (La), yttrium (Y), praseodymium(Pr), chromium (Cr), tin (Sn), gallium (Ga), indium (In), rhodium (Rh),magnesium (Mg), lithium (Li), barium (Ba), calcium (Ca), strontium (Sr),manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), rubidium (Rb) andrare earth metals, as a major component thereof, said metallic partsincluding an element selected from the group consisting of copper (Cu),gold (Au), silver (Ag), platinum (Pt), palladium (Pd), iridium (Ir) andosmium (Os) not less than 1 atomic % and not exceeding 50 atomic % ofsaid resistance adjusting layer.